I would agree, if you just started playing WoW 2 weeks ago, I would play the game normally, as it was originally intended to play. You will get to learn the game and other classes, how pve and pvp works and so on. Plus once you decide to multi box, you can use that 70 of yours to help your new multi boxed toons.

I'd suggest a prot pally or a frost mage if you want to boost your other toons later.